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Biomedical subjects

R Chauhan

Publications and source records attributed to R Chauhan.

12 recordsLinked to original sources
PubMed2006

Profile of chronic hepatitis B virus in children in India: experience with 116 children.

BACKGROUND: Hepatitis B virus (HBV) infection in children is mostly asymptomatic and therefore the disease burden is likely to be under appreciated. There is limited information on the profile of chronic HBV infection in children from the Indian subcontinent. METHOD: In 116 (male:female 89:27) children, aged <15 years, with persistent HBsAg positivity for more than 6 months, a clinical, biochemical, virological and histological assessment was carried out. RESULTS: At presentation, 21.6% of children were symptomatic, with icterus in 12%. Features of decompensation such as ascites (7%) and gastrointestinal (GI) bleed (5%) were noted uncommonly. Five (4.3%) children had hepatocellular carcinoma (HCC) at presentation. Elevated alanine aminotransferase (ALT) was observed in 76% of subjects (median 61; range 14-815). A significantly higher proportion of children with hepatitis B early antigen (HbeAg) positive status had higher histological activity index (HAI) (84% vs 16%, P < 0.001) and fibrosis score (80% vs 20%, P = 0.007). A strong positive correlation was noted between aspartate aminotransferase (AST), ALT, HBV-DNA and histological severity of the disease (HAI > or =4, fibrosis > or =2). Median HBV-DNA levels were significantly higher in the HBeAg positive compared to the HBeAg negative group (25.6 vs 0.7 pg/mL, P = 0.004). Seventy-four percent of the mothers had evidence of past or present HBV infection. CONCLUSIONS: Majority of the children with chronic HBV infection are asymptomatic at presentation. HBeAg positive status reflects histologically more severe disease, and a higher level of HBV-DNA. Almost two-thirds of the children may have acquired their HBV infection perinataly.

Adolescent↗
PubMed2004

Over-expression of TATA binding protein (TBP) and p53 and autoantibodies to these antigens are features of systemic sclerosis, systemic lupus erythematosus and overlap syndromes.

The aim of this study was to determine the expression levels of p53 and TATA binding protein (TBP) and the presence of autoantibodies to these antigens in Asian Indian patients with systemic sclerosis (SSc), overlap syndromes (OS) and systemic lupus erythematosus (SLE). Fifty patients with SSc, 20 with OS, including mixed connective tissue diseases (MCTD), 20 with SLE, 10 disease controls (DC) and 25 controls (C) were studied. The over-expression of p53 and TBP antigen was determined quantitatively by sandwich enzyme-linked immunosorbent assay (ELISA), varies between four- and sevenfold higher in patients with SSc, OS and SLE, in comparison to DC and C. The expressed protein antigens were not present as free antigens but as immune-complexes. Autoantibodies to p53 were detected by ELISA in 78% subjects with SSc, 100% with OS and 80% with SLE. Autoantibodies to TBP were observed in 28% patients with SSc, 25% with OS and 15% with SLE. In comparison to healthy controls, the titre of antibodies to p53 was significantly higher in patients with SSc (P = 0.00001) than the patients with OS (P = 0.00279) and SLE (P = 0.00289), whereas the titre of antibodies to TBP was higher in patients with OS (P = 0.00185) than the SLE (P = 0.00673) and the SSc (P = 0.00986) patients. Autoantibodies to p53 and TBP were detected in all these patients and the levels of these two autoantibodies showed weak negative correlation with each other. We propose that the over-expression of these antigens might be due to hyperactive regulatory regions in the p53 and TBP gene.

Adult↗
PubMed2001

Characterization of the Mycobacterium tuberculosis H37Rv alkyl hydroperoxidase AhpC points to the importance of ionic interactions in oligomerization and activity.

An alkyl hydroperoxidase (AhpC) has been found frequently to be overexpressed in isoniazid-resistant strains of Mycobacterium tuberculosis. These strains have an inactivated katG gene encoding a catalase peroxidase, which might render mycobacteria susceptible to the toxic peroxide radicals, thus leading to the concomitant overexpression of the AhpC. Although the overexpressed AhpC in isoniazid-resistant strains of M. tuberculosis may not directly participate in isoniazid action, AhpC might still assist M. tuberculosis in combating oxidative damage in the absence of the catalase. Here we have attempted to characterize the AhpC protein biochemically and report its functional and oligomerization properties. The alkyl hydroperoxidase of M. tuberculosis is unique in many ways compared with its well-characterized homologues from enteric bacteria. We show that AhpC is a decameric protein, composed of five identical dimers held together by ionic interactions. Dimerization of individual subunits takes place through an intersubunit disulphide linkage. The ionic interactions play a significant role in enzymic activity of the AhpC protein. The UV absorption spectrum and three-dimensional model of AhpC suggest that interesting conformational changes may take place during oxidation and reduction of the intersubunit disulphide linkage. In the absence of the partner AhpF subunit in M. tuberculosis, the mycobacterial AhpC might use small-molecule reagents, such as mycothiol, for completing its enzymic cycle.

Biopolymers↗
PubMed2001

Phacoemulsification cataract extraction and posterior chamber lens implantation in patients with uveitis.

PURPOSE: This study reports outcomes of phacoemulsification cataract extraction and posterior chamber intraocular lens implantation within the capsular bag in patients with uveitis. METHODS: We retrospectively reviewed the charts of 32 patients (39 eyes) with uveitis who underwent phacoemulsification cataract extraction and posterior chamber intraocular lens implantation by two surgeons at The Cleveland Clinic Foundation from January 1990 to June 1998. Patients with less than 3 months of follow-up were excluded. RESULTS: Diagnoses of uveitis included idiopathic (15 eyes), sarcoidosis (10 eyes), pars planitis (four eyes), CMV retinitis (two eyes), Fuchs heterochromic iridocyclitis (two eyes), syphilis (two eyes), and one eye each of tuberculosis, Crohn's disease, HLA-B27 associated, and acute retinal necrosis. Average follow-up was 20 months (range, 3 to 63 months). Best-corrected visual acuity improved in 37 eyes (95%). Average improvement was 4 +/- 3 Snellen acuity lines (range, 1 to 10 lines). Thirty-four eyes (87%) attained final visual acuity better than or equal to 20/40. Visual loss occurred in one eye (3%) with CMV retinitis. No improvement in visual acuity was seen in one eye (3%) that developed a retinal pigment epithelial detachment. Posterior capsule opacification occurred in 24 eyes (62%), 12 of which required Nd:YAG capsulotomy (31%). Other postoperative complications included recurrence of uveitis (41%), cystoid macular edema (33%), epiretinal membrane formation (15%), and posterior synechiae (8%). CONCLUSIONS: Phacoemulsification cataract extraction with posterior chamber intraocular lens implantation is safe in patients with uveitis. The incidences of recurrence of uveitis, cystoid macular edema, epiretinal membrane, and posterior synechiae were lower than those reported previously for extracapsular cataract extraction.

Adult↗
PubMed2001

Haematological investigations on fishes infested with fungal growth.

Considerable changes have been observed in the haematological parameters of Labeo rohita, Mystus cavasius, Nandus nandus and Puntius sarana infested with Aphanomyces sp., Saprolegnia parasitica, Achlya prolifera and Dictyuchus monosporus, respectively. Substantial decline have been observed in the number of erythrocytes and lymphocytes. The number of granulocytes and monocytes were noticed significantly increased. The amount of haemoglobin has also been decreased drastically in all the cases.

Animals↗
PubMed1998

Real-time intraoperative transesophageal echocardiography--how useful? Experience of 5,016 cases.

OBJECTIVE: To evaluate transesophageal echocardiography (TEE) as an intraoperative monitoring modality and to assess its safety, reliability, and overall utility in real-time use during cardiac surgery. DESIGN: Prospective, observational cohort study performed from January 1993 to June 1997. SETTING: Operating room of a tertiary care hospital for cardiology and cardiovascular surgery. PARTICIPANTS: Five thousand and sixteen adult patients with acquired heart disease, who underwent 1,356 valve procedures and 3,660 coronary artery bypass graftings (CABGs). INTERVENTIONS: All patients were monitored with radial artery and pulmonary artery catheters, along with continuous TEE monitoring with a multiplane transducer. MEASUREMENTS AND MAIN RESULTS: Prebypass imaging yielded unsuspected findings that either helped or modified the surgical plan in 158 of 1,356 valve procedures (11.65%) and in 993 of 3,660 CABGs (27.13%). There were 3,217 TEE-guided hemodynamic interventions in 944 patients (25.79%) in the CABG group and 629 in 142 patients (10.47%) in the valve group. TEE was the sole guiding factor in initiating therapy in 23.53% of events, whereas it was supportive to other monitoring modalities in 76.46% of events. Postbypass TEE identified the need for graft revision in 29 patients (0.8%), intra-aortic balloon pump (IABP) requirement in 29 patients (0.8%), and inadequate valve repair in 28 patients (2.08%). For the entire series, 38.78% of patients benefited from prebypass and 39.16% from postbypass use of TEE. There were no complications attributable to the use of TEE in the entire series. There was 87% concordance between online interpretation by a trained anesthesiologist and offline analysis by a cardiologist. CONCLUSION: Intraoperative TEE is useful in formulating the surgical plan, guiding various hemodynamic interventions, and assessing the immediate results of surgery. It is safe and the results are reliable in the hands of trained anesthesiologists.

Cardiac Surgical Procedures↗
PubMed1996

The 'small spleen' in malaria.

A cardinal feature of malaria, splenomegaly, is usually absent in adult patients who have already suffered from falciparum malaria or who are natives of an endemic falciparum zone. This is an attribute of the past episode of clinical or sub-clinical malaria which usually results in regression of the splenic size to below-normal. An ultrasonographic evaluation of spleens was done in 90 healthy adult males, who had suffered from vivax (n = 28) or falciparum (n = 25) malaria in the past, except the controls (n = 22) and natives from an endemic falciparum area (n = 15) who never suffered from malaria. Their ultrasonographic details of spleens, including the size, were compared. Besides other conspicuous differences in the ultrasonographic picture, spleen size was found significantly decreased (p < 0.01) in the group who had been affected by P. falciparum malaria; the smallest measured 7.8 cms. In P. vivax group the decrease was not significant (p < 0.1), but was highly significant in inhabitants of endemic falciparum region (p < 0.001). The present study establishes the 'Small Spleen' and looks at echotexture pattern variations thereof for the first time.

Adult↗
PubMed1992

Fungal transmission of a potyvirus: uredospores of Puccinia sorghi transmit maize dwarf mosaic virus.

Maize dwarf mosaic virus (MDMV) and maize rust, Puccinia sorghi Schw., occur as natural infections on cultivated maize in South Africa. P. sorghi often occurs as a secondary late infection on maize plants which have already been infected with MDMV earlier in the season, either seed or aphid transmitted. When MDMV isolates from maize plants naturally infected by both virus and fungus were propagated by sap inoculation in plant growth rooms, residual uredospores in the sap gave rise to the development of uredia under conditions of high humidity. When uredospores developing on MDMV-B-infected plants were germinated on virus free maize seedlings, these plants became infected with MDMV-B. Similarly, when uredospores, originating from maize plants infected with MDMV-A, were scattered onto virus free maize seedlings, these plants became infected with MDMV-A. The presence of virus on uredospores in infected plant tissue was visualized by indirect immunofluorescence. Identification of virus infection was by DAS-ELISA and immunoelectro-blotting utilizing strain-specific antisera. Virus transmission occurred between closely situated plants which had no actual contact (unaided transmission). MDMV-B transmission by uredospores, to new maize seedlings, has been maintained for three successive years (1988-1991) in a plant growth room. The MDMV-B isolate remained sap and non-persistently aphid transmissible.

Animals↗